Field of the Invention
The present invention relates to an accessory used for image capturing and an image capturing apparatus which are capable of communicating with each other, and particularly to an accessory and an image capturing apparatus which are capable of switching a use communication mode.
Description of the Related Art
Japanese Patent Laid-open No. 2013-167895 discloses an interchangeable lens (hereinafter also referred to as “a lens”) as an accessory for image capturing which detects a voltage level of a communication terminal shared with an image capturing apparatus (hereinafter referred to as a camera) and the lens when communicating with the camera in synchronization with an exposure timing of the camera. When the voltage level of the communication terminal has not changed for a certain time, the lens determines that following communication is switched to communication in synchronization with the exposure timing.
Furthermore, Japanese Patent Laid-open No. 2009-258558 discloses a camera system that switches a communication mode between a camera and a lens to one of communication modes such as UART and USB when a moving image capturing mode is selected as an image capturing mode of the camera.
However, the lens disclosed in Japanese Patent Laid-open No. 2013-167895 may perform a false determination when the voltage level of the communication terminal shared with the camera and the lens is changed by an external noise. On the other hand, the camera system disclosed in Japanese Patent Laid-open No. 2009-258558 switches the communication mode in response to a single command from the camera, and thus reception of an external noise simultaneously with reception of the command prevents the lens from receiving the command correctly. In this case, the camera switches the communication mode whereas the lens does not switch the communication mode, thereby preventing correct communication between the camera and the lens.